Mass spectrometry can be used to determine the molecular mass and formula of organic compounds from a small sample without the use of light. During mass spectrometry, molecules are ionized by bombarding them with high-energy electrons which causes bond breaking. The masses of the fragment ions and their relative abundances provide information about the molecular structure. Mass spectrometry involves ionizing molecules, separating the ions by mass, and detecting them to produce a mass spectrum that reveals the molecular mass.

5. ELECTRON IMPACT RADICAL CATION ONLY CATIONS ARE CARRIED TO DETECTOR CATION RADICAL BOND-BREAKING

6. MS of METHANE So what does a typical ms looks like???? m/z

7. C H H H H H . . H C . . . . . . H H

8. . . . . . H . . H C . . . . . . H H +

11. Mass Spectrometer =>

14. M.S. Spectrum 142 g/mol – 113 g/mol = 29 g/mol

15. M.S. Spectrum Why is there a small peak at 109 g/mol?

16. The GC-MS => A mixture of compounds is separated by gas chromatography, then identified by mass spectrometry.

19. Isotopic Abundance => 81 Br

20. Mass Spectrum with Sulfur =>

21. Mass Spectrum with Chlorine =>

22. Mass Spectrum with Bromine =>

25. End of Chapter 12